How severe is CVE-2026-9087?

CVE-2026-9087 has a CVSS 3.x base score of 6.4, rated medium severity. It is exploitable over network with high attack complexity, requires low privileges and user interaction. Impact on confidentiality is high, integrity high, and availability none.

Is CVE-2026-9087 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (23rd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-9087?

CVE-2026-9087 affects Redhat Build Of Keycloak. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-9087?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2026-9087 have an EU (EUVD) identifier?

Yes. CVE-2026-9087 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-31134.

When was CVE-2026-9087 published?

CVE-2026-9087 was published on 2026-05-20 and last updated on 2026-06-26.

CVE-2026-9087

CVE-2026-9087 is a medium-severity vulnerability in Redhat Build Of Keycloak with a CVSS 3.x base score of 6.4. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-639.

Key facts

Severity: Medium (CVSS 3.x base score 6.4)
EPSS exploit prediction: 0% (23rd percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-31134
Weakness: CWE-639
Affected product: Redhat Build Of Keycloak
Published: 2026-05-20
Last modified: 2026-06-26

Description

A flaw was found in Keycloak. The cross-session verification proof is keyed only by (local userId, idpAlias) and is not bound to the upstream identity that was actually verified, so a second upstream account on the same IdP can consume it and get linked to the victim's local account.

Frequently asked questions

What is CVE-2026-9087?: A flaw was found in Keycloak. The cross-session verification proof is keyed only by (local userId, idpAlias) and is not bound to the upstream identity that was actually verified, so a second upstream account on the same IdP can consume it and get linked to the victim's local account.
How severe is CVE-2026-9087?: CVE-2026-9087 has a CVSS 3.x base score of 6.4, rated medium severity. It is exploitable over network with high attack complexity, requires low privileges and user interaction. Impact on confidentiality is high, integrity high, and availability none.
Is CVE-2026-9087 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (23rd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-9087?: CVE-2026-9087 affects Redhat Build Of Keycloak. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-9087?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-9087 have an EU (EUVD) identifier?: Yes. CVE-2026-9087 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-31134.
When was CVE-2026-9087 published?: CVE-2026-9087 was published on 2026-05-20 and last updated on 2026-06-26.

References

Affected products (1)

cpe:2.3:a:redhat:build_of_keycloak:-:*:*:*:-:*:*:*

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